A law that every public sector helpline, and all companies above a certain size must have a 'press 1 for us to call you back' option. And also have the 'you are number x in the queue' information when you are on hold.
Currently on hold to HMRC for 40 mins so far and I can't concentrate on doing anything else properly. Every time the music stops for the 'thank you for waiting' message I slightly jump just in case it's someone actually answering the phone.